For the production of a wide range of objects, amongst which containers made of plastic materials, such as bottles or jars for foodstuffs made of PET, PP, HDPE, PEN (or other composite polymers, for example blends, multi-layers, etc.), various devices have been developed for fixing the semi-finished products in the blow-moulding stage to systems such as overhead conveyors, chain conveyors and the like (or else systems generically referred to as “endless load-conveying surface conveyors”), and for carrying them through the various workstations downstream of the blow-moulding station (for example, stations for thermal treatment, coating, or other forms of treatment).
In certain situations, the gripping of the moulded object during the operations of loading or unloading of the conveyor may prove particularly delicate, since the moulded object may be particularly subject to damage, for example, when the material of a blow-moulded bottle is not yet perfectly cross-linked, or a coating or paint is not yet cross-linked or hardened.
Moreover, in several known coating processes, the blown bottles or other objects to be coated are spinned to a relatively high rate while conveyed through a coating spray tunnel in order to achieve a uniform distribution of the spray on the bottle surface, and/or are conveyed at high velocity in high capacity production chains. Hence it's generally desired to have devices which can fasten the bottles, or other objects to be coated, to an overhead conveyer, firmly and securely holding them in spite of high spin rates or conveying velocity.
At the same time, in certain cases it may be necessary to protect the chuck and/or some parts of the moulded object from certain forms of treatment, for instance, to exclude some areas from a coating treatment and protect them.